Fuel-pump



March 17, 1925. 1,530,247 J. E. DOUGLAS FUEL PUMP 3 Sheets-Sheet 1' gru/vento@ March 17, 1925. 1,530,247

J. E. DouGLAs run. rum

Filed Apr-11' 18,1923

3 Sheets-Sheet 2 NmHvm. Gaim.

one end of the block or casing 6 are plugs 22 and 23 screwedl into the ends of the cylinders to enable access to be had thereto for the purpose of cleaning or removing the plungers.

The pipe 5 conveying oil from the oil tank 4 is connected to the pipe section 24 projecting from the lower forward portion of the. pump casing 6, in which pipe section is a seat for the downwardly seating check valve. 25 having the perforated guard plate 26 there above communicating directly with the open end of the lower cylinder 15. A vertically disposed threaded opening` 27 is made in the pump easing or block to receive the pipe section 24 and also a threaded block 28 containing' also a similarly downwardly seating check valve 29 communieating` at its under side with the open end of the loweil cylinder 15. This block likewise is associated with a perforated guard plate 30 for the valve which allows the oil to be pumped upwardly into a transverse passage 31 leading to the open adjacent end of the upper pump cylinder 16 and to the pipe 8 which delivers the fuel to the nozzle, the pipe being provided with a screw threaded connection 32 by which it is secured in fluid type fashion to the casing. A valve seat. 33 for a valve 34 is secured above the intermediate portion of the passage 81 and in a recess 35 made substantially coaxial with the lower threaded opening 27, this recess communicating at its upper end 36 with the pipe 7 for returning fuel to the tank 4. The check valve seats downwardly also and is normally held closed by a rotary stop 37 carried upon a shaft 38 transversely 'journaled through the easing and projecting at one end as for instance as seen in Figure 4 where it receives an arm 39 having a spring 40 enga-ged with its lower end in tending to urge the arm in a counterclockwise direction to hold the stop 37 normally against the check valve 31. The spring 40 is preferably a relatively strong spring to withstand the pressure developed in the pump.

The arm 39 also projects above the shaft 38 to which it is fixed and is pivotally coupled to a link 41 having at its free end a yoke 42 occupied by a tapering or wedge shaped bar 43 depending from the governor shaft 13 and pivoted thereto as indicated at 44 in Figures l and 5 in order that the bar 43 may swing in the same direction with the link 41 and in the direction of the slot in the yoke which/also contains a finger 45 projecting upwardly from a rock shaft 46 extending transversely through the casing and having a continuous oscillating movement imparted by the moving parts of the engine. The finger 45 is so disposed that it bears'against one wedge-shaped side face of the bar 43, while the bar engages against the end of the yoke. A coil spring 47 is looped about the yoke and a stud 48 secured to the pump block 6 and a like stud 49 may be provided to hold one end of the spring 40.

One mechanism for securing the reciprocation of the pump plungers and also the oscillation of the rock shaft 4G is illustrated in Figures l and 3 in which an eccentric 50 upon the crank shaft 2 is utilized to movethe eccentric strap 51 and also this eccentric strap the arm 52 secured thereto and lying along one side of the pump casing 6. At its free end this arm 52 is slotted as indicated at 53 receiving therein a pin 54 which projects from an arm 55 upstanding from the pump shaft 21 upon which the pump pinion is mounted. Uaon this same shaft 21 is an eccentric 55 having a strap secured to an arm 56 which is pivotally coupled as indicated at 57 to a depending arm 5S upon the rock shaft 46.

ln operation, as the engine shaft 2 rotates it will revolve the governor balls 10 and also reciprocate the rod 52 by which an oscillating movement is communicated through the arm 55 and shaft 21 to theV pinion 20. Due to the gear connection between the pinion and the plungers 17 and 18, the latter will beV reciprocated in the cylinders 15 and 16 but the plungers will move in constantly relatively reverse directions. lhen for instance the lower plunger 17 is moving to the right in Figure 2, the upper plunger 18 is moving to the left. The plunger' 17 in thus moving to the right lifts the check valve 25 and draws in a supply of fuel oil from the tank through Jthe pipe 5. On the neXt subsequent movement to the left, the plunger 17 displaces this supply of fuel and forces it upwardly past the check valve 29 to the upper cylinder 16 which is oering a constantly enlarging chamber because ofthe receding of the upper plunger 18. Upon the next stroke.V of the upper plunger, the check valve 29 isV closed and the upper check valve 34 beingheld against its seat by the stop 37, the fuel oil will be forced into the pipe 8 and conveyed to the nozzle end where it is sprayed into the combustion chamber of the motor. Any excess of oil is returned to the fuel tank by way of the pipe 7 whenever thel check valve 34 is permitted to open, as when the stop 37 is withdrawn. This function is accomplished by the action lof the governor in combination with the wedge bar 43 and the finger 45. The finger 45 is constantly oscillated together with the shaft 21 and the finger striking the bar which rests against the link 41 serves to turn through the fraction of a rotation the shaft 38. This recurs during each cycle of the engine and the timing of the. removal of tige stop 37 from the check valve 34 is arranged by the position of the inclined edge or edges the governor'balls 10 iiy outand'lowerfthe shaft 'and with it the bara?) softhat the wider portion of the latter 'is presentedto the fingera which willv thereupon pstI ke the bar earlier and cause an earlier movement of the trip. The oil will thus be ev'-b abled to escape back'to the tankV and at' high speeds a lesser amount 'of oil is thus furnished tothe combustion chamber and the governoriwill consequently restrict the `speed of the engine within a predetermined maximum. As the engine sneed decreases the bar 43 willbelifted. so that itsflower tapered edge will recedefurther away from the finger 45 and the stop 37v`will be opened onlv at a laterA period. i

It will be appreciated thatwitli the double plunger pump of 'the' character described,l

the stress will devolve not only upon the plungers, but also upon the actuating gear because of the oil pressure upon both pistons and the oil will further serve to lubricate the pistons, the casing or block of the pump being made fluid tight Wherever joints or shaft bearings are mounted therein.

It will further be appreciated that the position of the eccentric on the main shaft controls the time of injection while the speed of the engine through the governor controls the amount of injection or in other words the governor does not control the timing of injection as is done in the case of present engines of this type.

It is also to heI noted that excessive pressure in front of the upper plunger resulting from the stoppage of the nozzle will open the relief valve 34 by overcoming the spring pressure and this movement is allowed by the slotted yoke42.

It is obvious that various changes and modifications may be made in the details of construction and design of the above specifically described embodiment of this invention Without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claims:

lVhat is claimed is:

1. A fuel pump for internal combustion engines comprising an initial pump ar ranged in connection with a source of fuel supply, a final pump in communication with the initial pump, a check valve between the pumps opening toward the final pump, said final pump having a relief port in communication with the source of supply, a relief valve normally closing said relief port, positive stopmeans engaging said relief valve to hold the same closed during the major period of thevcycle of operations of the engine, means driven by the engine for periodically removing said positive stop means `from engagement with said relief valve,imeans for varying the time and dura-l tion of the removal of said stop meansfroni the valve VVwith reference to each cycle of' operations of the engine, and-meansy whereby said linal pump is placed in communication Lwitlitlie fuelnozzlebf the enginey i 25A fuel pump forinternal combustion engines comprising .a casing having initial and finalk pump chambers with a' passage connecting'the endsof the chambers, a check valve, in said passage opening away from the initial pump chamber, said initialgpump chamber l'ieing in connectionr with a sourcey of fuel supply,l said final pumpy chamber being in connection with ythe fuel nozzle of the engine, pistons :fitted to reciprocate in said vvchambers, a coni# 'mon means for alternatelyreciprocating said pistons from movement derived from," the engine, said casing havin V la` relief port in connectioii-'Ywith Y'the' final-V pump chamber, a relief valve normally closing said port, a rotary stop adapted to positively engage said relief valve to hold the same closed, positive means driven by the engine for acting to shift said rotary stop away from the valve, and means whereby the period at which said sto-pis shifted and the duration of time the stop is lield away from said valve may be varied directly in proportion to the speed of the-engine.

3. In combination with an internal com-k bustion engine and a governortherefor, of a fuel pump comprising an initial pump in communication with a source of fuel supply, a linal pump in connection with the initial pump and with the fuel nozzle of the engine, a check valve between the pumps opening toward the final pump, a relief port in connection with the final pump, a relief valve normally closing said relief port, a rotaryA stop adapted to positively engage said relief valve to hold same seated, a slotted link connected to said rotary stop, an oscillating finger moved by the yengine engaging iii said slotted link, and a wedge connected for variable movement to said governor and projecting between the slotted link and the finger for varying the time period and duration of the opening of the relief valve during each cycle of operations in terms of the speed of the engine.

4t. In combination with an internal combustion engine and a governor therefor, a fuel pump comprising an'riiiitial pump in connection with a source of fuel supply, a final pump in connection with the engine and with the initial pump, a check valve between the pumps closing toward said initial pump, a relief valve for-the final pump, a rotary stop positively engaging said relief valve, strong resilient means for normally holding said rotary stop against the valve, a link connected to said stop, a vibrating linger moved by the engine, and

a wedge shiftable with the governor and disposed between said finger and the link for changing the timing and dura-tion of the opening of the relief valve.

, 5. In combination with an internal combustion engine, and a governor therefor, a fuel pump comprising initial and final pumps having communication, a check valve between the pumps opening toward the final pump, said initial pump being in connection with a source of fuel supply, said final pump being in connection with the engine and with the source of fuel supply, a normally closed relief valve for preventing the pumping of the fuel back to the supply from the final pump, a rotary stop normally7 engaging and Closing said relief valve, relatively strong resilient means acting to hold said stop in closed position, a link connected to said stop, a vibrating finger, a wedge carried by the governor and moving variably between said finger and the link, and` an eccentric motion for the vibrating finger derived from the movement of the engine.

6. A fuel pump comprising means for drawing in and ejecting a supply of fuel, a relief valve in the pump, a stop associated with the relief valve, means for normally and yieldably holding the stop and valve in closed position, a slotte-d arm connected with said stop, a vibrating finger operating in the slotted yoke and driven continuously by movement derived from the engine and for moving the yole to remove the stop from the relief valve onee during each cycle of operation of the engine, and a wedge adjustably carried by the governor and adapted to fit between the slotted arm and said vibrating finger for varying the time period at whatever finger will open the stop and retain the stop opened.

JOHN ERLE DOUGLAS. 

